Vacuum-tube apparatus



Feb. ,1 1,525,844

w. c. WHITE VACUUM TUBE APPARATUS Filed July 5, 1920 Srfif/VGTH OFM/IG/VET/C F/ELD His Attorney.

Patented Feb. 1%, "i925,

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WILLIAIVI 0. WHITE, F SGHENEGTADY, NEXV YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

VACUUM-TUBE arraaa'rus.

Application filed July 3, 1920. Serial No. 393,813. a"

T0 aZZ whomz't may concern:

Be it known that I, WILLIAM C. VVHrrn, a citizen of the United States, residing at Schenectady, in the county of Schenectady,

5 State of New York, have invented certain new and useful Improvements in Vacuum- Tube Apparatus, of which the following is a specification.

'My present invention relates to improve ments in vacuum tube apparatus, and par ticularlyin the type of apparatus commonly known as electron discharge apparatus.

- The object of my invention is to provide a simple, convenient and efficient apparatus for and method of controlling by means of a magnetic field an electron current between two electrodes of an electron discharge device. 7 I r In carrying-my invention into effect I produce astream of electrons between a cathode and plate electrode of an electron discharge device and cause the velocity of this stream to be greatly decreased as the electrons approach the plate electrode. By

producing acmagnetic field in the region adjacent the plate electrode which acts upon these slowly moving electrons, it'is possible bymeansof acomparatively weak magnetic field to produce a substantial variation in the electron current received by the plate electrode.

The novel features which I believe to be characteristic of my invention are set forth -with particularity in the appended claims,

the invention itself, however, both as to its organization and=method of operation, to-

t hereof, will best be understood by reference toLthe following description taken in'connec- 40 tion :withfthe accompanying drawing in which Fig; 1 is a view partly broken'away .of-an-.-electron discharge device which may be employed in carrying out my invention;-

' Fig 2 is a typical characteristic curve showing the relation between the plate current andthe strength of the magnetic field, and Fig. is a diagrammatic illustration of a circuit connectionrwhich may be employed in carrying inyinvention into effect.

theidrawing comprises an evacuated receptaole- 1 containing a filamentary cathode 2, a grid electrode 3'in the form of a helix sur- "rounding the 'cathode 2, and a plate electrode 4 in the form of a cylinder surrounding the ether with further objects and advantages The electron discharge device illustrated in electrode and grid. In the'circuitarrangement indicated in Fig. 3 the battery 5 supplies the 'heating current for the cathode 2 for heating it to incandescence in order to furnish a supply of electrons for theoperation of the device, the variable resistance 6 being inserted for varying theheati'ng cur rent. Abattery 7 having its positive terminal conn'ectedto the grid 3 furnishes a means for n' aintaini'ng the grid'3 at a desired positive'potential with respect "to the cathode whereby the electrons emitted from the cathode will be given ahigh velocity. A battery 8 may be connected between the cathode and plate electrode 4 for maintaining the plate electrode at a desired potential with respect to the cathode. In some cases this may bepositive and in other'casesit may be negative, and again this battery may be omitted entirely. In the operation of the device a portion of the electrons emitted from the cathode 2 strike the grid 3 while an'otl1er"portion of them will pass between the t'urn's'of the grid 8' and move toward the plate electrode l. As these electronsap proaclrthefplate electrode 'l, however, their velocity will greatly de'crease'because of the fact that the plate l is maintained at a potential which is either negative with respect to the" cathode, or in the extreme case is only slightly positivewith respect to the cathode. If a magnetic field is set up in the space be tween the electrodes in a direction'paralll to the 'major'axis' of the electrodes by passing current through the winding 9.surrounding the receptacle 1, it will be possible to readily control thefl'ow of electrons which reach the plate electrodet. I 'It has heretofore be n known that it is possible by means of a magn'eticfield'tovary the paths of movin'gelectrons and in this way vary the electron 'current' between the two electrodes; In the operation" of this type of devicefhowever, it has been customary in the past "to provide an appreciable potential difference? between, the two electrodes and thereby cause the electrons to move between the two ele'ctrode'swith a high velocity. Under these conditions a comparetively strong magnetic field is required to j produce a sufficient deflection of the ele'c trons to vary the electroncurrentbetween the electrodes. With the arrangement have just 'described,liowever, it ispdssibl'e by means of a magnetic field of small intensity such as may be produced by means of a weak variable current which it is desired to amplify, to produce appreciable cl'ianges in the electron current between the cathode and plate electrode.

The curve of Fig. 2 shows the relation between plate current and the strength of magnetic field in a device such as that I have just described. It is to be observed that a variation in the strength 01 the magnetic field in either direction produces a corresponding variation in the plate current. It will be noted that the maximum current in this case instead of occurring at zero value of the magnetic field, occurs with a given value of magnetic field in what is indicated as the negative direction. This is due to the fact that the magnetic field set up by the heating current of the cathode acts upon the electrons and tends to deflect them to some extent. As a result of this fact the slope of the characteristic curve at zero value of the magnetic field is such that the device may be operated to advantage at this point. In the case indicated by this characteristic curve, the grid electrode was given a positive potential of forty volts and the plate battery 8 was omitted entirely, In the operation of this device as an amplifier of variable currents the currents to be amplified are supplied to the winding 9 and the amplified current may be observed in a tele phone 10 or other suitable indicating device in circuit between cathode and plate electrode.

I am aware that it has heretofore been proposed to operate a device oi the general construction indicated in the drawing in such a way that secondary electrons will be emitted from the plate electrode st in sutficient numbers to produce a negative resistance characteristic between cathode and plate electrode. It has been proposed to vary the value of this negative resistance by means of a magnetic field applied in the manner which I have indicated. In this case, however, it is necessary to cause the electrons to strike the plate electrode with a high velocity in order that secondary electrons may be emitted. As a result, a strong magnetic field is required to produce any appreciable deflection oi' the electrons. In the operation of the apparatus in the manner which I have described, the electrons are caused to strike the plate electrode with a velocity so low that secondary electrons will not be emitted.

While I have illustrated only one form of device for carrying out my invention and I have indicated in a diagrammatic way a single circuit connection for utilizing my invention, it will be apparent to those skilled in the art that my invention is by no means limited to the particular device or circuit arrangement shown, but that many modifications in the form of the apparatus used as well as in the circuit arrangements employed may be made without departing from the scope of my invention, as set forth in the appended claims.

W hat I claim as new and desire to secure by Letters Patent of the United States, is,-

1. The combination in an apparatus of the class described of an electron discharge device comprising an electron emitting cathode, a grid electrode and a plate electrode, means for producing a high velocity stream of electrons between the cathode and grid electrode, means for producing a stream of electrons which move between cathode and grid at a high velocity and approach the plate electrode with a decreasing velocity, and means for producing a magnetic field in the space between the grid electrode and the plate electrode.

2. The combination in an apparatus of the class described of an electron discharge device comprising an electron emitting cathode, a grid electrode and a cylindrical plate electrode surrounding the grid electrode, a source of potential connected in such a way that the grid electrode is rendered positive with respect to the cathode, means for maintaining the plate electrode at a potential lower than that required to produce secondary electron emission therefrom, and means for producing a magnetic field in thespace between the grid electrode and the plate electrode.

3. Means for amplifying variable currents comprising an electron discharge device having an electron emitting cathode, a grid electrode and a plate electrode, means for producing a stream of electrons which flow from cathode to grid electrode at a high velocity and approach the plate electrode with a much lower velocity, and means for producing by the current to be amplified a magnetic field in the space between the grid electrode and the plate electrode.

l. Means for amplifying variable currents comprising an electron discharge device having an electron emitting cathode, a grid electrode and a cylindrical plate electrode surrounding the grid electrode, a source of potential connected in such a way that the grid electrode is maintained positive with respect to the cathode, means for maintaining the plate electrode at a potentiallower than that required to produce secondary electron emission therefrom, and means for producing by the current to be amplified a magnetic field in the space between the grid electrode and the plate electrode.

5. The method o't operating an electron discharge device having an electron emitting cathode, a grid and a plate electrode surrounding the grid elect-rode which con sists in producing a high velocity stream of electrons between cathode and grid electrode, causing electrons which pass through the grid electrode to approach the plate electrode with a velocity so low that they will be incapable of producing secondary electrons when they strike the plate electrode, and varying the current between cathode and plate electrode by producing a magnetic field in the space between the electrodes in a direction parallel to the major axis of the electrodes.

6. The method of operating an electron discharge device having electron emitting cathode, a grid and a plate electrode, which consists in producing la stream of electrons which move at high velocity in the space be tween the cathode and grid electrode, causing the velocity of the electrons which pass through the grid to greatly decrease as they approach the plate electrode, and varying the current between cathode and plate electrode by producing a magnetic field in the space between the electrodes.

7. The method of amplifying a variable current by means of an electron discharge device having an electron emitting cathode, a grid and a plate electrode surrounding the grid electrode which consists in producing a high velocity stream of electrons between cathode and grid electrode, causing the electrons which pass through the grid electrode to approach the plate electrode with a velocity so low that they will be incapable of producing secondary electrons when they strike the plate electrode, and varying the current between cathode and plate electrode by producing by means of the current to be amplified a magnetic field in the space between the electrodes in a direction parallel to the major axis of the electrode.

8. The method of amplifying a variable current by means of an electron discharge device having an electron emitting cathode, a grid and a plate electrode, which consists in producing a stream of electrons which move at a high velocity between cathode and grid electrode, causing the velocity of the electrons which pass through the grid to greatly decrease as they approach the plate electrode, and varying the current between cathode and plate electrode carried by the electron stream by producing by means of the current to be amplified a magnetic field in the space between the electrodes.

In witness whereof, I have hereunto set my hand this 1st day of July, 1920.

WILLIAM C. lVHITE. 

